LONG BEACH, Calif. (AP) -- What began as an after-school fight between two young girls over a boy exploded into a homicide investigation Monday, when authorities said a 10-year-old died of a head injury after the confrontation with an 11 year-old classmate.
The finding rattled the already shaken school community at Willard Elementary, where student Joanna Ramos attended the fifth grade. She died Friday, about six hours after a brief fight with another girl in an alley near the school in a working-class neighborhood in the port city of Long Beach.
Joanna, who would have turned 11 on March 12, underwent emergency surgery for a blood clot on her brain late Friday after she began vomiting and complained of a headache, her older sister, 17-year-old Vanessa Urbina, told The Associated Press.
Joanna was unconscious by the time she arrived at the emergency room, but hospital staff revived her three times before she went into surgery for the clot, Urbina said.
"After surgery the doctor said she was still alive, and then a few minutes later he comes back and tells us that her heart stopped and they couldn't bring her back," Urbina said, crying as she sat on the steps of the school near a memorial of flowers and balloons.
Police said they have made no arrests and were conducting an investigation that will be presented to prosecutors when it's completed. Coroner's Lt. Fred Corral said Ramos died of blunt force trauma to the head, but he didn't immediately have further details about her injuries.
Doctors say head injuries suffered in fistfights can often lead to delayed bleeding when a punch results in a torn vein. That can then lead to a clot when blood collects on the surface of the brain.
Dr. Keith Black, a neurosurgeon at Cedars-Sinai Medical Center, said he sees such injuries all the time, but it's uncommon to see it in a child, especially a young girl.
"This is rare, in that I've never seen it in a female, certainly not in a female adolescent," said Black, who was not involved in Joanna's medical care.
Still, he said, a blow to the head from one young girl to another could "absolutely" be sufficient to cause enough trauma to lead to death.
Worried parents lingered as they dropped off their children Monday in a light rain and wondered aloud how the school, tucked a few blocks off a major city street, could have become the scene of such unexpected violence.
Victoria Pyles said her daughter started classes at the school last week, after the family moved to the neighborhood. Her daughter likes the school, Pyles said, but now she isn't sure whether to leave her there.
"I'm just so confused at this moment, thinking should I take my daughter out of this school," Pyles said. "If this is what is going on, I don't like it. It's very scary."
School officials believe the fight occurred near the school in a 15-minute window between the time school let out and the start of Joanna's after-school program at 2:30 p.m., said Chris Eftychiou, a spokesman for the Long Beach Unified School District.
Joanna didn't have any visible injuries or show any signs of distress for about an hour, but she eventually told staff she felt unwell and was picked up by a relative, he said.
Urbina, the older sister, said Joanna's cousin picked her up. After he mother retrieved her, Joanna vomited in the car all the way home and told her mother she felt sleepy and wanted to go to bed.
Symptoms -- such as headache, nausea, lethargy -- may not set in for hours and people can mistakenly think that they're fine, Black said.
Typically, he said, the hit to the head would have to be fairly significant to cause a blood clot and often involves the head hitting walls or the ground, but a punch is enough.
"You can certainly get enough of an impact to get enough movement in the brain by a fist to tear a vein, if it's in the right location," Black said.
Police have said the fight lasted less than a minute, did not involve weapons, and no one was knocked to the ground. Detectives interviewed family and friends of both girls, but there was no indication that Joanna was bullied. Seven witnesses to the fight were being interviewed.
A friend of Joanna's saw her as she reported to the after-school program after the fight and said she had blood on her knuckles from wiping at a bloody nose, said Cristina Perez, the friend's mother.
Perez said her daughter, who is 10, heard about plans for the fight during recess earlier in the day and knew to stay away from the alley after school.
"We've just got to pay more attention to our kids too, not just dropping them off at the school. I'm always on my daughter, always," Perez, 30, said as she gathered with other concerned parents outside the school Monday. "I tell her, 'You see a fight (and) you stay away from it.'"
Perez and other mothers said their children told them the fight was over a boy.
"They took off their backpacks, and they put their hair in a bun, and then that's when they said 'go' and that's when they started hitting each other," Joanna's friend and classmate Maggie Martinez, who watched the fight, told KNBC.
Martinez and other friends said they tried to stop the fight, but were held back by boys who were watching and wanted it to continue.
Urbina said her sister was a happy child who liked to sing, dance and watch soap operas and loved having her hair curled. She had asked her parents to take the whole family to an amusement park to celebrate her birthday.
Joanna also helped Urbina care for her infant son and would get up in the middle of the night to fix him his bottle, Urbina recalled.
"She was so young for this to happen," Urbina said. "She was so happy and so many people loved her."
Fights involving young children, including girls, are increasing nationally, in part because of the wired world children now live in, said Travis Brown, a national expert on bullying and school violence.
Children used to have a disagreement at school and would have a night or a weekend to cool down, but social media and text messaging mean students can continue their dispute 24 hours a day, he said.
Social media sites also allow other students to weigh in and amplify the pressure to settle things in a public way, said Brown, who runs the website www.nobullytour.com .
"There was a time when a kid had a way to escape the things at school, but now there's no escape," he said. "That stuff just escalates to a point where it gets out of hand. This is an everyday occurrence."
Associated Press writers Robert Jablon, Alicia Chang and Andrew Dalton in Los Angeles contributed to this report.